Rural dwellings, and the like, not connected to a central or "city" water supply system utilize a water well and related system apparatus to provide water service. Such systems generally include a water well consisting of a vertical shaft extending from the service to some distance below the water line (generally into an underground aquifer or other water-bearing formation). This shaft is lined by a casing pipe having an annular space surrounding a water pipe. A pump is connected to the water pipe below the water level within the casing pipe.
In one prior art system, water is pumped through the water pipe into the plumbing system of the dwelling or the like. In another prior art system, the water pipe is connected to a pit within an insulated enclosure wherein the pit is utilized to feed the plumbing system. In still another prior art system, the water pipe is connected to a pitless unit which may or may not be housed within a pressure tank.
Systems employing pressure tanks may be housed in an insulated enclosure, or may be buried below the frost line. The depth of the frost line will vary depending on the climate in which the system is employed. Therefore, it would be desirable to provide a pressure tank for a water system, that may be buried in the ground at various depths.
In order to pressurize a water system and supply a volume of water to a location, a water tank capable of being pressurized is needed. To pressurize water in a tank, some portion of the tank volume must be air, which stores the pressure energy. In a typical application, approximately one half of the tank may be filled with water and one half filled with air.
One drawback to such a system is that the air in the tank is absorbed by the water, thereby dissipating the potential energy stored by the pressurized air, and eventually allowing the tank to become full of water, thus preventing further pressurization.
One method to overcome this problem is to periodically pressurize the tank externally using pressurized air to get the water level back to its optimum level. This method is troublesome, time consuming. The period of time between external pressurization depends on water usage, however, periods of approximately once per month are typical.
Another method of overcoming the problems associated with the loss of air pressure due to absorption of air into the water is to use an internal rubber bladder to separate the air from the water. This method has the drawback of being costly to manufacture and purchase, and when the bladder wears out, it is costly to purchase and reinstall.
Yet another method is to use a float that opens a vent to allow air out of the tank for filling purposes and then, at a predetermined float level, shuts off the vent, leaving a portion of the tank full of air. Through continued filling of the tank, the remaining air trapped in the tank compresses, storing the energy for future use.
Systems using a pressure tank typically employ an air volume control valve within the tank to release excess air introduced into the system and maintain a proper volume of air within the tank. Prior art air volume control valves usually comprise a tube extending into the pressure tank to allow airflow into or out of the pressure tank. This tube includes a restricted orifice disposed in its lower end. A float assembly positioned beneath the orifice prevents airflow out of the tank through this orifice when the water level within the tank is sufficiently high to force the float against the orifice. Similarly, when the water level in the tank is sufficiently low, the force of gravity causes the float to fall to a lowered position away from the orifice permitting excess air to flow out of the tank.
One drawback to this method is that the float is not buoyant enough to completely seal off the valve. A problem experienced with prior art air volume control valves is that, due to submersion in water or other liquid, corrosion, mineral deposits, sediment, and other solids in the water may plug the orifice and prevent proper venting of air form the tank. Should this happen, air may be trapped within the tank. This trapped air may displace the water in the tank, lowering the water level and causing the system to function poorly. Thus, it is desirable to provide an improved air volume control valve wherein the valve orifice is not susceptible to being obstructed by sediment and other solids in the water.
It would, therefore, be desirable to provide a water system wherein the air valve is located outside the tank, and most preferably above the ground, to ensure that it is not plugged by debris or deposits. It would also be desirable to provide an improved float mechanism to ensure complete sealing of the air release port.